1. Field of the Invention
The present invention relates to a keyboard system applied to an electronic device using a keyboard for inputting information and, more particularly, to a keyboard system applied to a compact computer such as a portable computer or a pocket computer which can be easily carried.
2. Description of the Related Art
In recent years, a personal computer has been decreased in size and weight, and has been easily carried. In addition, a high-performance, multifunctional personal computer has been manufactured. The high-performance, multifunctional personal computer can be realized by a system arrangement whose functions can be expanded by connecting an arbitrary input/output device to a connection port for an external device. In particular, in reagent years, a personal computer such as a lap-top type personal computer or a book type personal computer which can be driven by a battery and has a large-capacity memory device such as a hard disk drive (HDD) or a RAM (Random Access Memory) pack has been popularly used in various fields. In this manner, a multifunctional computer system which can be easily carried is not only used on a desk but also used to be held by an operator in his/her hand. When information is input in this state, since one hand holds the system, the information must be input by the other hand.
A keyboard applied to a conventional personal computer is an 84-key keyboard, 101/102-key keyboard or the like. In each of these keyboards, 80 or more keys are arranged. For this reason, when information is to be input by one hand information cannot be efficiently input by an operator with one hand.
In addition, a conventional keyboard requires a certain space for arranging keys. This space poses a problem when a portable computer is further decreased in size. When a present inputting method is used, at least 40 keys are required in a keyboard. For this reason, an operator cannot input information with one hand.
As described above, as a method of reducing the number of keys of the keyboard in order to decrease the size of the keyboard or input letters with a single hand, "keyboard apparatus for inputting Japanese with a small number of keys" is proposed by FUJITSU LTD. (Jpn. Pat. Appln. KOKAI Publication No. 4-139520). In this publication, an apparatus for inputting Japanese on the basis of the Roman letters is disclosed, and a keyboard apparatus for inputting English letters is also disclosed. In this English letter inputting keyboard apparatus proposed by FUJITSU LTD., in order to reduce the number of keys, each English letter is assigned to a corresponding one of the keys arranged on the keyboard apparatus, and not only each English letter can be input by depressing a corresponding one of the keys, but also each of the English letters which cannot be respectively assigned to the keys of the keyboard can be input by simultaneously depressing corresponding two of the keys of the keyboard. That is, in the keyboard apparatus described above, after it is detected that an arbitrary key (to be referred to as a first key hereinafter) is depressed, depression of the next key is waited for a predetermined period of time. In this case, when another key (to be referred to as a second key hereinafter) is depressed within the predetermined period of time, a key code representing an English letter assigned by the combination of the first and second keys is output. On the other hand, when any key is not depressed within the predetermined period of time, a key code representing the English letter assigned to the first key is output.
In this keyboard apparatus, however, in order to input the English letter assigned to simultaneous depression of the two keys, after the first or second key is depressed, the other key must be depressed within the predetermined period of time. Therefore, an operator must recognize in advance a key or combination of two keys to which each English letter is assigned. For this reason, in order to input English letters, an operator must have skills in the input operation of this keyboard. For example, after one key of the combination of two keys assigned to an arbitrary letter is depressed, if the predetermined period of time has passed while the other key is searched on the keyboard, the keyboard apparatus recognizes that the letter assigned to the key depressed first is input. For this reason, only an operator who has satisfactorily learned the key arrangement of the keyboard apparatus can efficiently perform the letter input operation.